Arrangement of power-grounds in package structures
A structure includes a redistribution structure, which includes a bottom layer and a plurality of upper layers over the bottom layer. The redistribution structure also includes a power-ground macro extending from a topmost layer in the plurality of upper layers to a bottommost layer in the plurality of upper layers, and a metal pad in the bottom layer and overlapped by the power-ground macro. The metal pad is electrically disconnected from the power-ground macro.
1. A method comprising:
placing a device die over a carrier;
encapsulating the device die in an encapsulant;
planarizing the encapsulant to reveal metal pads in the device die; and
forming a redistribution structure over the device die and the encapsulant, wherein the redistribution structure comprises a bottom layer in contact with the device die, and a plurality of upper layers over the bottom layer, and wherein the redistribution structure comprises:
a first power-ground macro extending from a topmost layer in the plurality of upper layers to a bottommost layer in the plurality of upper layers; and
a first metal pad in the bottom layer and overlapped by the first power-ground macro, wherein the first metal pad is electrically disconnected from the first power-ground macro.
2. The method of claim 1 , wherein the redistribution structure further comprises:
a second power-ground macro extending from the topmost layer in the plurality of upper layers to the bottommost layer in the plurality of upper layers; and
a second metal pad in the bottom layer and overlapped by the second power-ground macro, wherein the second metal pad is electrically connected to the second power-ground macro.
3. The method of claim 1 , wherein the forming the first power-ground macro comprises forming a solder region in the topmost layer in the plurality of upper layers.
4. The method of claim 1 further comprising de-bonding the carrier from the device die and the encapsulant.
5. The method of claim 1 , wherein the plurality of upper layers comprise four layers.
6. The method of claim 1 further comprising:
before the redistribution structure is formed, copying the first power-ground macro from a library and placing the first power-ground macro into a design layout; and
laying out the first metal pad in the design layout, wherein the redistribution structure is formed to implement the design layout.
7. The method of claim 6 , wherein the placing the first power-ground macro and the laying out the first metal pad are performed in separate steps.
8. The method of claim 6 further comprising:
placing a plurality of power macros and a plurality of ground macros into the design layout;
laying out a blanket metal pad overlapped by the plurality of power macros and the plurality of ground macros; and
patterning the blanket metal pad in the design layout as a first plurality of metal plates and a second plurality of metal plates separated from each other.
9. The method of claim 8 , wherein one of the first plurality of metal plates encircles the second plurality of metal plates.
10. The method of claim 9 further comprising
laying out a first via in the design layout and connecting the one of the first plurality of metal plates to one of the power macros; and
laying out a plurality of second vias in the design layout and connecting the second plurality of metal plates to respective ones of the plurality of ground macros.
11. The method of claim 8 , wherein the blanket metal pad is in a layer higher than the first metal pad.
12. A method comprising:
placing a device die over a carrier;
encapsulating the device die in an encapsulant;
planarizing the encapsulant to reveal metal pads in the device die; and
forming a redistribution structure over the device die and the encapsulant, wherein forming the redistribution structure comprises:
forming a plurality of dielectric layers and a plurality of conductive layers in the plurality of dielectric layers, wherein the forming the plurality of conductive layers comprises:
forming a bottom layer of conductive features, wherein the bottom layer comprises:
at least one first conductive feature; and
at least one second conductive feature, wherein patterns of the at least one first conductive feature are different from the at least one second conductive feature;
forming a first power-ground macro overlapping the at least one first conductive feature; and
forming a second power-ground macro overlapping the at least one second conductive feature.
13. The method of claim 12 further comprising:
copying and placing the first power-ground macro and the second power-ground macro from a library into a design layout; and
laying out the bottom layer of conductive features in the design layout, wherein the redistribution structure is formed to implement the design layout.
14. The method of claim 12 , wherein the first power-ground macro and the second power-ground macro are identical to each other.
15. The method of claim 12 , wherein the metal pads of the device die comprise metal pillars.
16. The method of claim 12 , wherein the bottom layer of conductive features has a top surface level with a top surface of one of the plurality of dielectric layers.
17. A method comprising:
placing a device die over a carrier;
encapsulating the device die in an encapsulant;
planarizing the encapsulant to reveal metal pads in the device die; and
forming a redistribution structure over the device die and the encapsulant, wherein the redistribution structure comprises:
a plurality of lower dielectric layers over the device die;
a first metal pad in a bottom layer of the plurality of lower dielectric layers;
a plurality of upper dielectric layers over the plurality of lower dielectric layers; and
a power-ground macro extending from a topmost layer in the plurality of upper dielectric layers to a bottommost layer in the plurality of upper dielectric layers, wherein the first metal pad is overlapped by the power-ground macro, and wherein the first metal pad is electrically disconnected from the power-ground macro.
18. The method of claim 17 , wherein the redistribution structure comprises:
a second metal pad in the bottom layer and vertically misaligned from the power-ground macro, wherein the second metal pad is electrically connected to the power-ground macro.
19. The method of claim 17 , wherein the redistribution structure is formed layer-by-layer.
20. The method of claim 17 further comprising:
copying the power-ground macro from a library and placing the power-ground macro into a design layout; and
laying out the first metal pad in the design layout in a step that is separate from the copying and placing, wherein the redistribution structure is formed to implement the design layout.